As an information display device substitutable for liquid crystal display (LCD), information display devices with the use of technology such as an electrophoresis method, an electro-chromic method, a thermal method, dichroic-particles-rotary method are proposed.
As for these information display devices, it is conceivable as inexpensive visual display device of the next generation from a merit having wide field of vision close to normal printed matter, having smaller consumption with LCD, or having a memory function, and spreading out to a display for portable device and an electronic paper is expected. Recently, electrophoresis method is proposed that microencapsulate dispersion liquid made up with dispersion particles and coloration solution and dispose the liquid between faced substrates, and also it is expected.
However, in the electrophoresis method, there is a problem that a response rate is slow by the reason of viscosity resistance because the particles migrate among the electrophoresis solution. Further, there is a problem of lacking imaging repetition stability, because particles with high specific gravity of titanium oxide is scattered within solution of low specific gravity, it is easy to subside, difficult to maintain a stability of dispersion state. Even in the case of microencapsulating, cell size is diminished to a microcapsule level in order to make it hard to appear, however, an essential problem was not overcome at all.
Besides the electrophoresis method using behavior in the solution, recently, a method wherein electro-conductive particles and a charge transport layer are installed in a part of the substrate without using solution is proposed. [The Imaging Society of Japan “Japan Hardcopy '99” (Jul. 21-23, 1999) Transaction Pages 249-252] However, the structure becomes complicated because the charge transport layer and further a charge generation layer are to be arranged. In addition, it is difficult to constantly dissipate charges from the electro-conductive particles, and thus there is a drawback on the lack of stability.
As one method for overcoming the various problems mentioned above, an information display device comprising an information display panel is known, which has one or more cells formed in an isolated manner from one another by partition walls and accommodating display media and a plurality of image display elements, in which the display media are sealed between opposed two substrates, at least one of the two substrates being transparent, and, in which the display media, to which an electrostatic field is applied, are made to move so as to display information such as an image.
At first, as shown in FIG. 14a, a rear substrate 51 is prepared, on which electrodes B1-B4 for supplying power to cells forming respective information display portions and electrodes A1-A4 for connecting the connection terminals of the outer circuit are arranged. In addition, as shown in FIG. 14b, a transparent front substrate 52 is prepared, on which transparent electrodes F1-F4 for supplying power to the cells forming respective information display portions are arranged. Then, as shown in FIG. 14c, an anisotropic conductive adhesive 53 is arranged on the rear substrate at an outer portion of the information display portion. The anisotropic conductive adhesive 53 has conductivity only at the portions indicated by a symbol◯ at which the electrodes A1-A4 and the electrodes F1-F4 of the front substrate 52 are intersected. Finally, as shown in FIG. 14d, the rear substrate 51 and the front substrate 52 are stacked with each other through the adhesive 53, so that the electrodes F1-F4 of the front substrate 52 are electrically derived from the electrodes A1-A4 of the rear substrate 51. It should be noted that a numeral 54 shows the image display portion.
In the information display device having the construction mentioned above, since only the anisotropic conductive adhesive 53 is used for connecting the rear substrate 51 and the front substrate 52. Therefore, a secure connection cannot be achieved both in electric manner and in mechanical manner, and thus there is a drawback such that reliability cannot be obtained. Moreover, the information display device having the construction mentioned above has a construction such that the electrodes A1-A4 and B1-B4 are arranged on one surface of the rear substrate 51. Therefore, the following steps are necessary. That is, as shown in FIG. 15a, the rear substrate 51 and the front substrate 52 are stacked. Then, as shown in FIG. 15b, all sides of the stacked substrate are cut out, and further the end portion of the front substrate 52 is cut out while corresponding portion of the rear substrate 51 is remained, so that the portion of the electrodes A1-A4 and B1-B4 indicated by a symbol W are exposed. Then, as shown in FIG. 15c, the connection terminals of an outer circuit 55 are connected to the exposed portion of the electrodes A1-A4. As a result, there is a drawback such that a machining becomes difficult and a wide non-displaying surface exists.